Flat Roof Insulation Board R Value

R value of various materials.

Flat roof insulation board r value. For a 1 inch board equivalent of 6 r value. 2020 insulation cost estimate foam board insulation prices. Thickness inches r value in i p imperial rsi r value in metric 0 5. Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1 93721. This material offers the highest r values about r 6 to 6 5. The average cost of flat roof insulation is 0 67 per square foot for 1 inch thick polyiso with 6 r value.

To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826. Working with home insulation boards insulation panels typically come in 4x8 foot sheets. Smaller sizes are also available. It is top quality and the most cost effective product for your flat roof.

They re much lighter and easier to work with than plywood sheets. We recommend having at least 20 r value worth of material for optimal energy efficiency. Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. Conditioned per atsm c1289 test method astm c5181 2.

Know exactly how much you need with our project calculators. You should of course see the manufacturer provided technical data sheet for the r value of specific products. High quality rigid foam insulation that is properly installed will greatly improve ventilation eliminate drastic temperature fluctuations inside the home and protect from leaks. R value measures how well certain building insulation materials can resist heat.

Here are the best insulation materials along with prices features and r values. R value chart for enerfoil tm rigid foam faced insulation. To convert rsi to r value multiply the rsi by 5 67826. The higher the r value the greater the insulation performance.

Combining different types of insulation to increase r value. State applicable energy ashrae zone minimum r value state local ms mississippi ashrae 90 1 2010 2 r 20 3 r 20 state local mo missouri 2012 iecc 4 r 25 5 r 25 state only mt montana 2012 iecc 6 r 30. Closed cell polyisocyanurate foam technology provides additional insulation value r value of 2 5 with lightweight and low water absorption characteristics. When determining how much insulation you need don t guesstimate calculate.

Minimum insulation r value requirements non residential above roof deck. Products with foil facing help the panels resist moisture vapor.